This invention relates to load elevating devices, and more particularly to an oil rig lift having a supporting substructure operably powered by the rig for movement from a collapsed, oil rig loading position to an elevated, oil rig supporting position.
In the oil field it is desirable to elevate the base of the oil derrick from the ground in order to provide a work area under the base allowing for installation of necessary valves, fittings, blowout preventers, etc. about the oil wellhead. Early on such a work area was provided by a reinforced cellar dug about the wellhead with the derrick floor then forming a ceiling of this cellar. Another method included placing a fixed elevated platform above the oil wellhead to allow the crew working access under the elevated oil rig. The platform utilizes a fixed supporting substructure comprising a plurality of box-like sections of heavy steel girders and braces with each section being bolted one to the other at the wellhead location. Notwithstanding the time, trouble and expense of such platform assembly it is still necessary to properly position the oil rig/derrick on the elevated platform--a difficult and dangerous job considering the tremendous derrick weight.
In response to the desire for efficient movement of the entire oil rig from location to location, portable oil rig assemblies including the derrick and attendant machinery are in use today. However, there still remains the problems of efficiently elevating the portable oil rig to a position above the oil wellhead in a manner to assure a proper alignment of the oil derrick with the wellhead therebelow. One response has been a collapsible substructure having a top frame positioned at an initial relatively low profile upon which the oil rig/derrick is placed. Once the rig/derrick is in place the entire top frame is laterally shifted and simultaneously elevated to position the derrick above the wellhead. However, the lateral displacement of this top frame with the significant oil rig load thereon for alignment above the wellhead raises the problem of lateral load shifting and limits the ability to easily achieve a required vertical alignment of the derrick with the wellhead disposed therebelow.
In response to these problems we provide a substructure, having collapsed and elevated modes, which is particularly adapted for supporting an oil rig with derrick thereon. The substructure utilizes a base mat with a wellhead aperture therein, a horizontal top frame positioned in a parallel relationship to the base mat and an intermediate, bifurcated frame comprising first and second traveling subframes therein. Linking the base mat, traveling frames and the top frame are a plurality of pivotal leg members swingable through vertically disposed arcs relative to the base mat therebelow. In the collapsed condition the traveling frames are in a longitudinally spaced-apart relationship and are generally horizontally adjacent the base mat. The top frame is also horizontally adjacent the traveling and base frames which presents a low profile to the substructure allowing for easy transfer of the oil well rig from a flatbed truck to the top frame. Upon transfer the oil derrick is aligned with the wellhead as presented through the wellhead aperture therebelow.
Operably associated with the traveling frames is a block and tackle arrangement utilizing a plurality of pulleys on each traveling frame with a steel cable trained therearound. Upon attachment of the free end of the cable to the derrick hook, operation of the oil derrick's block and tackle assembly operates the substructure's block and tackle which causes the traveling subframes to move one towards the other. In response to such longitudinal movement the plurality of pivotal leg members swing through their respective arcs which longitudinally shifts and vertically displaces the traveling frames and elevates the top frame with the derrick load thereon. The pivotal leg members, as connected in parallel between the base mat, each traveling frame and top frame, present a parallel linkage structure intercoupling the traveling and top frames so that the respective frames remain parallel during their movement.
Collapsible end sway braces are also employed and restrain the loaded top frame against longitudinal shifting to thereby confine the displacement of the top frame to strictly vertical movement. Once the traveling frames reach a side-by-side relationship they are locked together to present an intermediate support frame to the now fully elevated top frame. Accordingly, a working area is presented below the elevated derrick and about the oil wellhead allowing for installation of the necessary valves, blowout preventers and the like.
To lower the substructure preparatory to relocating the rig at another site, the traveling frames are unlocked and the weight of the oil rig itself urges the pivotal leg members to swing downward causing a concurrent downward movement of the top frame and traveling subframes towards their collapsed positions. A hydraulic piston/cylinder assembly regulates the downward movement so as to buffer the collapsing movement of the entire substructure. In its collapsed condition the oil rig is then easily shifted from the top frame to a flatbed truck known as an "oil field float" for site relocation. Moreover, the collapsed substructure itself requires only a single float for transport as a unit to another site with the assurance that the substructure loaded on the float will not interfere with overhead obstacles such as bridges, power lines and the like.
It is therefore a general object of this invention to provide a substructure for displacing a load between a first relatively ground adjacent position and a second elevated position.
Another general object of this invention is to provide a substructure, as aforesaid, in which said load is an oil rig including oil derrick and attendant machinery therein.
Still another general object of this invention is to provide a substructure, as aforesaid, which elevates the oil derrick from the relatively ground adjacent position to present a working space about the oil wellhead.
A still further general object of this invention is to provide a substructure, as aforesaid, in which the attendant machinery of the oil rig operably engages the substructure to lift the substructure and bootstrap the oil rig/load to the elevated position.
Another object of this invention is to provide a substructure, as aforesaid, which displaces said load strictly vertically without inducing any lateral movement.
Still another object of this invention is to provide a substructure, as aforesaid, which includes a pair of traveling frame members movable toward and away from each other to effect an upward and downward displacement of said load.
Still another object of this invention is to provide a substructure with traveling frames, as aforesaid, which utilizes a ground supporting base mat or frame and a load supporting top frame with said top frame being vertically displaced in response to said movement of said traveling frames.
Another object of this invention is to provide a substructure, as aforesaid, which utilizes linkage means intercoupling said top, traveling and base frames to cause the top and traveling frames to displace upwardly or downwardly in response to said traveling frame movement.
A further object of this invention is to provide a substructure with linkage means as aforesaid, in which said downward displacement of said traveling and top frames is induced by said load thereon.
Still another object of this invention is to provide a substructure with linkage means, as aforesaid, which maintains a parallel relationship among said frame members during movement thereof.
A still further object of this invention is to provide a substructure, as aforesaid, which utilizes end sway braces to preclude horizontal shifting of said load during elevating operation of the substructure.
Another object of this invention is to provide a substructure, as aforesaid, which utilizes a buffer assembly to control the downward movement of said frames and thus the collapsing movement of said substructure.
Still another object of this invention is to provide a substructure, as aforesaid, which utilizes a block and tackle to effect said movement of said traveling frames.
A further object of this invention is to provide a substructure with block and tackle, as aforesaid, which is engageable with the block and tackle of the associated oil rig to allow said oil rig to raise itself to the elevated position.
A still further object of this invention is to provide a low profile to said substructure, as aforesaid, during the collapsed mode thereof to allow for easy transfer of said oil rig from and to an adjacent transport vehicle.
A more particular object of this invention is to provide a substructure of a low profile, as aforesaid, transportable by a single vehicle as a unit between sites and without interference with overhead obstacles on the route therebetween.
Another object of this invention is to provide a substructure, as aforesaid, having an area in the base frame for surrounding the wellhead and allowing for transport of materials to and from the wellhead area.
Still another object of this invention is to provide a substructure, as aforesaid, which has a base frame therein with rail means thereon allowing for easy transport of materials to and from the oil wellhead.
Other objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings, wherein is set forth by way of illustration and example, an embodiment of this invention.